Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
quoc van » quoc va, quoc ban, quoc lan
cuoc van » cuoi van, luoc van, cuu van
hieu ve » hieu va, hieu van
cao hoc » co hoc, cho hoc, chat hoc
ty nang » ky nang, ty xang, ty hang
cua cau » cua cac, cua chu, cua cay
anh va » hanh va
va cua » va chua, via cua, ca cua
ve ca » ve cac, ve cai, ve cau

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) OR (toc sach)) ty nang cao hoc. hieu ve ca ((cuoc van) or (quoc van)) anh va cua cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) ty nang cao hoc. hieu ve ca ((cuoc van) OR (quoc van)) anh va cua cau*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) ty nang cao hoc. hieu ve ca ((cuoc van) or (quoc van)) anh va cua cau*".